1. Field
The presently disclosed subject matter relates to an LED lighting unit including a plurality of LED light sources and a plurality of reflectors and a vehicle lamp using the LED lighting unit. The LED lighting unit can be a high-power LED lighting unit having a favorable light distribution that can be used for vehicle lamps such as a headlight and the vehicle lamps using the same that can be perceived as a single, integrated lighting surface.
2. Description of the Related Art
Various LED lighting units using a reflector have been used for vehicle lamps in recent years. One reason is that LED light sources can emit variously-colored lights while the structure thereof can be thin and small in size. A high-power LED light source can be used for a vehicle lamp in order to reduce the number of LED chips. However, when a high-power LED light source is used for a vehicle lamp, the LED lighting units may include a heat sink with the LED light source in order to radiate a heat generated from the LED light source.
A conventional headlight combining a plurality of high-power LED light sources, each including a heat sink, with a plurality of reflectors is disclosed in patent document No. 1 (Japanese Patent Application Laid Open JP2007-305575). FIG. 8 is a schematic side cross-sectional view showing a basic structure of a conventional headlight combining a plurality of high-power LED light sources with a plurality of reflectors disclosed in patent document No. 1. The headlight 20 includes a projector headlight 22 using a high-power LED light source 22b and a reflector-type headlight 23 using a second LED light source 23b, which is located under the projector headlight 22.
The projector headlight 22 can include: a high-power white LED light source 22b; a heat sink 25 connected to the LED light source 22b; an elliptical reflector 22d in which a first focus thereof is located near the LED light source 22b; a projector lens 22e which has a focus thereof located near a second focus of the elliptical reflector 22d; and a shade 22f having a top edge located near the focus of the projector lens 22e. 
In the conventional projector head light 22, a part of the light emitted from the light source 22b directly passes through the projector lens 22e and another part of the light indirectly passes through the projector lens 22e by reflecting on the elliptical reflector 22d. In this case, because the shade 22f can shield an upward light of the lights, the projector headlight 22 can form a light distribution pattern having a cut-off line formed by the shade 22f. 
The reflector-type headlight 23 can include: a second white LED light source 23b; a heat sink 26 connected to the other LED light source 23b; and a parabolic reflector 23d in which a focus thereof is located near the other light source 23b. Therefore, the reflector-type headlight 23 can emit a horizontal light under the cut-off line in the same direction as that of the projector headlight 20. The amount of light emitted from the projector headlight 20 using the LED light source 22b may be small in comparison with a headlight using a HID light source. Light emitted by the reflector-type headlight 23 can supplement the light emitted by the projector headlight 22 in the headlight 20.
However, when viewing the illuminated headlight 20 from the front of the vehicle, the light emitted from the projector headlight 22 and the light emitted from the reflector-type headlight 23 may be seen as separate headlights, and therefore the combined light may not be perceived as a single, integrated light distribution pattern.
In addition, because the headlight 20 includes heat sink 25 connected to the LED light source 22b and heat sink 26 connected to the other LED light source 23b, a space between the projector headlight 22 and the reflector-typed headlight 23 may be required. Therefore, the above-described lights may be perceived as two lamps that emit respective light.
Moreover, when the respective radiating efficiencies of their heat sinks 25 and 26 are increased with respect to each other, the space between the heat sinks 25 and 26 may become larger. Each of the headlights 22 and 23 can include an adjustment mechanism that can adjust an optical axis between these headlights 22 and 23. The space that may be required for the adjustment mechanisms may also contribute to the perception of that their two lamps emit the respective light separately. Thus, the conventional structure may include a problem such that it may not be perceived as a single, integrated lighting surface.
A conventional signal light that combines a plurality of high-power LED light sources, including a heat sink, with a plurality of reflectors is disclosed in patent document No. 2 (Japanese Patent Application Laid Open JP2002-93206). FIG. 9 is a schematic side cross-sectional view showing a basic structure in a conventional signal light combining a plurality of high-power LED light sources with a plurality of reflectors disclosed in patent document No. 2.
The conventional signal light 30 includes: a circuit board 31; a plurality of high-power LED light sources 32 mounted on the circuit board 31; a insulating sheet 33 having a thermal conductivity located underneath the circuit board 31; a heat sink 34 located underneath the insulating sheet 33; and a chassis 35 including a plurality of reflectors attached to the circuit board 31 together with both the insulating sheet 33 and the heat sink 34 so as to locate the LED light sources 32 in the reflectors thereof.
The light-emission may be very bright in the conventional signal light 30 because a direct light of the light emitted from the LED light sources 32 and a reflective light via the reflectors of the chassis 35 can be illuminated in a direction towards the light-emission of the signal light 30. In addition, the radiating efficiency may become high because the heat sink 34 can be located underneath the circuit board 31 mounting the LED light sources 32 via the insulating sheet 33 having a thermal conductivity.
However, when seeing the light-emitting state of the signal light 30 from the light-emitting direction, the light emitted from the reflectors and a part of the chassis 35 without the reflectors may be seen as a respective separate lighting surface and therefore their lights may not be perceived as a single, uniform lighting surface.
Thus, a light diffusing member may be required over the signal light 30. Moreover, when the emitting area of the signal light 30 becomes large and/or curved, the signal light 30 may include problems such as an increase in the number of the LED light sources, an increase in the driving current, a plurality of the signal lights 30 may be required, and so on.
The above-referenced Patent Documents are listed below and are hereby incorporated with their English abstracts in their entirety.    1. Patent document No. 1: Japanese Patent Application Laid Open JP2007-305574    2. Patent document No. 2: Japanese Patent Application Laid Open JP2002-93206
The disclosed subject matter has been devised to consider the above and other problems, characteristics and features. Thus, an embodiment of the disclosed subject matter can include an LED lighting unit that can be perceived as a single, integrated lighting surface and can be placed in a small casing while maintaining a high radiating efficiency. The disclosed subject matter can also include a vehicle lamp using the LED lighting unit, which can maintain a favorable light distribution with a simple structure.